Clinical Definition

CPAP therapy works by generating a positive pressure airstream that acts as a pneumatic splint for the upper airway. This constant pressure prevents the soft tissues in the throat from collapsing, thereby eliminating apnea and hypopnea events.

A CPAP system consists of three main parts:

  1. CPAP Machine: A small, quiet pump that takes in room air, pressurizes it, and delivers it at a prescribed setting.
  2. Hose: A flexible tube that connects the machine to the mask.
  3. Mask: A device that fits over the nose, mouth, or both, to deliver the pressurized air.

Etymology & History

The concept was invented by Dr. Colin Sullivan and colleagues in Sydney, Australia, in 1980. Their first publication in The Lancet in 1981 demonstrated the immediate reversal of obstructive sleep apnea with nasal CPAP, revolutionizing sleep medicine.

Reference Values & Interpretation

Normal Values

A normal value is the prescribed pressure setting, typically ranging from 4 to 20 cm H2O. The goal is a therapeutic pressure that effectively splints the airway open.

Abnormal Values

Abnormal values would be pressures that are too low (leading to residual apneas) or too high (causing discomfort, air swallowing, or treatment-emergent central apneas).

How It's Measured

The required pressure is determined via a Polysomnography (PSG) with CPAP titration or an Auto-titrating PAP (APAP) device.

Role in Diagnosis

CPAP is not a diagnostic tool but is used after a diagnosis of OSA has been established. The patient's response to a trial of CPAP can sometimes be diagnostic in itself, confirming that OSA was the cause of their symptoms.

Role in Treatment

CPAP is the gold standard for OSA treatment. The goal is to reduce the AHI to less than 5 events per hour and alleviate symptoms. It effectively prevents airway collapse, normalizes oxygen levels, and restores normal sleep architecture, thereby reducing the long-term health consequences of untreated OSA.

Associated Conditions

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Clinical Guidelines

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Latest Research & Updates

AI-Updated Weekly

Modern CPAP technology includes advanced features like auto-titration (APAP), expiratory pressure relief (EPR), integrated humidification, and wireless data monitoring. These innovations have significantly improved comfort and adherence compared to early devices.